Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dang nam » dong nam, dan nam, dung nam
dau tren » dau tien, dat tren, dau tieng
dang ma » dang mau, dang mam, dang mat
sach ty » sach y, sach tu, sach thu
cam luc » cam xuc, cau luc
hanh va » hang va
hieu ve » hieu va, hieu van
ve cam » ve cham, ve cac, va cam
luc va » duc va, tuc va, loc va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ty ((dang ma) or (dang nam)) hoi. hieu ve cam luc va ((hanh va) OR (hanh vi)) dau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty ((dang ma) OR (dang nam)) hoi. hieu ve cam luc va ((hanh va) OR (hanh vi)) dau tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty ((dang ma) or (dang nam)) hoi. hieu ve cam luc va ((hanh va) OR (hanh vi)) dau tren*".